Question

What pair is the solution of [ x-y=-3 and [2x+y=0

Answer 1

x - y = -3
2x + y = 0
----------------add
3x = -3
x = -3/3
x = -1

x - y = -3
-1 - y = -3
-y = -3 + 1
-y = -2
y = 2

solution is (-1,2)

Answer 2

x-y=-3---------No.1
2x+y=0-------No.2
No.1+No.2:3x=-3
x=-1
y=2